Add Automated Tests for src/mcp/client/sse.py and src/mcp/server/sse.py

[apappascs]

The files src/mcp/client/sse.py and src/mcp/server/sse.py implement the client and server functionalities for SSE transport, but there are no tests in the repository to verify their behavior.

Relevant Links:
PR: #83
Related Discussion: jlowin/fastmcp#69
Related Issue: #101

[dsp-ant]

Contributions here would be greatly appreciated. Feel free to send PRs.